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Re: [pcp] Culling code from libpcp

To: Greg Banks <gnb@xxxxxxxxxxx>, kenj@xxxxxxxxxxxxxxxx
Subject: Re: [pcp] Culling code from libpcp
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Thu, 6 May 2010 15:52:54 +1000 (EST)
Cc: pcp@xxxxxxxxxxx
In-reply-to: <4BE22833.4020605@xxxxxxxxxxx>
----- "Greg Banks" <gnb@xxxxxxxxxxx> wrote:
> > None of the various PCP libraries are thread safe.  This was a
> conscious
> > decision right at the very beginning (not an accidental oversight).
> ...
> Aha.  That's the situation I remember from my days digging around in 
> libpcp source, apparently it's not improved in the meantime.  That's

Heh, or rather "apparently it's not regressed in the meantime".  ;)

Putting locking and threading API calls throughout libpcp would be a
bit of a nightmare, and arguably overkill... and plenty of use of PDUs
happens between pmcd and pmdas too, so we're definately talking adding
useless overhead there (already "threaded" there!).

If this socket connection delay issue is a genuine problem for people
(as someone using pmchart everyday, with remote hosts around the globe,
I tend to find it *not* a major problem ... but maybe I'm just lucky!),
then my vote would be for separate processes per-context communicating
with a common graph/UI process via mmap or something like that.

cheers.

-- 
Nathan

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